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Calculation of transient electromagnetic field around a transmission line subjected to lightning strokes
, Article 2003 IEEE Power Engineering Society General Meeting, Toronto, Ont., 13 July 2003 through 17 July 2003 ; Volume 1 , 2003 , Pages 258-261 ; 0780379896 (ISBN) ; Porkar, S ; Jahromi, A. N ; Sharif University of Technology
2003
Abstract
In this paper, a new method for the calculation of electromagnetic fields around a transmission line subjected to a lightning strike is described and discussed. The electric fields and magnetic fields are presented graphically as a function of spatial coordinate, as a function of time and as a function of both. It is believed that this exact solution have not been published before. First, a double exponential lightning surge current is injected into a transmission line. Once The temporal variations of current is known, then electric and magnetic fields can be calculated by using the field expressions for electric dipoles over infinitely conducting ground. As the calculation was done for each...
Safety Assessment of the Transmission Towers Subjected to Natural Loads Including Earthquakes, Floods, Storms and Ice
, M.Sc. Thesis Sharif University of Technology ; Ghaemian, Mohsen (Supervisor)
Abstract
Electrical power is an inseparable part of human life. Therefore, design and analysis of electrical transmission towers have always been important for scientists. In common design methods due to the lightness of these structures only the wind load is considered and earthquake effects are neglected. On the other hand, regarding regulation No.2800 a lot of areas of Iran are located in earthquake zones. Therefore, it is necessary to evaluate the performance of these structures against earthquakes. In this research, regarding conducted studies, we decided to use incremental dynamic analysis method (IDA) in order to evaluate seismic performance of the tower. In sake of thoroughness of the...
Rigorous Calculation of Guided Modes in Photonic Crystal Waveguides and Contriving Homogenized Models
, M.Sc. Thesis Sharif University of Technology ; Mehrany, Khashayar (Supervisor)
Abstract
In this thesis an approximate method is proposed for analysis of two dimensional photonic crystal waveguides. In this method an equivalent impedance is assigned to photonic crystal regions and the waveguide region is modeled with a transmission line. Waveguide’s loss is also analysed and computed by this method. In other words the proposed method is able to determine the complex propagation constant of guided modes without computing any complex roots for dispersion equation. Although like any other approximate method, the accuracy of this method is dependent to some special conditions but it’s advantage over other numerical methods is its simplicity and its capability for waveguide designs....
Accurate fault location algorithm for series compensated transmission lines
, Article IEEE Transactions on Power Delivery, Piscataway, NJ, United States ; Volume 15, Issue 3 , 2000 , Pages 1027-1033 ; 08858977 (ISSN) ; Hadjsaid, N ; Ranjbar, A. M ; Feuillet, R ; Sharif University of Technology
IEEE
2000
Abstract
In this paper, an accurate fault location algorithm for series compensated power transmission lines is presented. Distributed time domain model is used for modeling of the transmission lines. The algorithm makes use of two subroutines for estimation of the fault distance - one for faults behind the series capacitors and another one for faults in front of the series capacitors. Then a special procedure to select the correct solution is utilized. Samples of voltages and currents at both ends of the line are taken synchronously and used to calculate the location of the fault. The proposed algorithm is independent of fault resistance and does not require any knowledge of source impedance. The...
Design of a Robust Active Controller to Suppress the Undesirable Vibration of Power Transmission Lines by Using the Intermediate Actuators and Optimization of Their Locations
, M.Sc. Thesis Sharif University of Technology ; Moradi, Hamed (Supervisor)
Abstract
Power transmission lines, which are responsible for the distribution and transmission of electrical energy from the power plant to the consumer areas, due to their characteristics such as long length and flexibility with low structural damping, face environmental irritations, especially the galloping phenomenon, causing many damages annually. In this study, it has been attempted to reduce the vibrations of power transmission lines by designing a robust active control and by using intermediate actuators in such a way that the failures of these lines can be prevented. For this purpose, linear modeling of the system and designing the controller using the pole replacement method have been done....
Design of a Modern Compact Transmission Line for Electrical Energy Transmission in Long Distances at 400 kV
, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi (Supervisor)
Abstract
With new progresses in technology, a growing need to power energy has emerged. In Iran most of power plants are far from cities and therefore expansion of power network will cause long transmission lines with high capacities which connect power plants to cities. There are three solutions for these kinds of lines: 1) two-circuit transmission lines 2) higher voltages 3) new forms of transmission lines (HVDC and compact). In this thesis some of these suggestions have been analyzed to find the best solution for a 560 Km transmission line in Iran.
Designing transmission lines has a lot of steps which all are related to each other. In this project a comprehensive algorithm has been utilized to...
Designing transmission lines has a lot of steps which all are related to each other. In this project a comprehensive algorithm has been utilized to...
Field Investigation and Monitoring of Land Subsidence Beneath Power Transmission Lines in Saturated and Unsaturated Zone
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
The increase in the amount of groundwater exploitation and climate changes has made land subsidence into one of the environmental problems and has caused many problems in various infrastructures such as urban areas, residential buildings, and vital arteries such as power transmission lines. Many areas of the country, especially areas with smooth topography such as plains where alluvium accumulates, due to excessive exploitation of groundwater resources and climate changes, are facing a decrease in the level of groundwater, an increase in the thickness of the unsaturated layer, and as a result, progressive subsidence. In particular, the destructive effects of land subsidence on power...
Robust fault location of transmission lines by synchronised and unsynchronised wide-area current measurements
, Article IET Generation, Transmission and Distribution ; Volume 8, Issue 9 , 1 September , 2014 , Pages 1561-1571 ; ISSN: 17518687 ; Ranjbar, A. M ; Sharif University of Technology
Abstract
This study presents a novel method for fault location of transmission lines by multiple fault current measurements. In contrast to conventional methods, it is proposed to utilise several current measurements, which may be far from the faulted line. The circuit equations of the network are used to express each fault current as a function of fault location. Fault location is then estimated using a least-squares estimation technique. To achieve a robust estimation of fault location, statistical hypotheses-testing is employed for identifying erroneous measurements. The method is applicable to both synchronised and unsynchronised measurements. Moreover, fault location can be estimated regardless...